blockcompanion

BlockCompanion

BlockCompanion shows a schematic in your world as ghost blocks so you can build it. It covers what Litematica does for placing and checking a build, with less on screen and simpler controls.

It is also the in-game companion to BlockDesigner, a Windows editor for Minecraft builds. It reads the projects and schematics BlockDesigner saves, saves builds from the world back as .schem files BlockDesigner opens, and with BlockDesigner's BlockCompanion Plugin the game and the app link up live.

BlockCompanion is in early development. Bug reports and ideas are welcome on the issue tracker.

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Requirements

| Loader |Minecraft |Java |Also needs | | -------- |--------- |---- |------------ | | Fabric |1.21.1 |21 |Fabric API | | Fabric |26.2 |25 |Fabric API | | Fabric |26.3 |25 |Fabric API | | NeoForge |1.21.1 |21 |nothing else | | NeoForge |26.2 |25 |nothing else | | NeoForge |26.3 |25 |nothing else |

Mod Menu is optional on Fabric and opens the settings screen from the mod list.

The mod is for the client. Putting it on a Fabric or NeoForge server as well (or the separate BlockCompanion Paper plugin on Paper 1.21.1 servers) adds shared schematics, AutoBuild and fetching blocks from linked chests on that server. Without it, the mod still works on vanilla servers, including easy place in survival.

Getting started

1. Install the jar for your loader and Minecraft version (plus Fabric API on Fabric).
2. Start the game once. It makes <game folder>/blockcompanion/schematics.
3. Put your BlockDesigner projects (.bdproj) and schematics (.schem, .litematic, .nbt) in that folder. The schematic screen has an Open folder button.
4. Press B, pick a schematic and click Load. It appears just in front of you.
5. Hold a stick and look at the schematic's box to move, turn and mirror it (see Controls below), then start building.

New to it? The title screen's BlockCompanion tutorial button opens a world made for learning: each step asks you to do one thing, tells you when you've got it, and takes you to the next. Chapter 1 covers the basics, chapter 2 your own schematics, chests, AutoBuild, sharing on a server and the live link to BlockDesigner.

A short guide also opens the first time you are in a world; the Guide button in the settings and in the BlockCompanion menu opens it again.

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Features

Schematics

• BlockDesigner's formats first: BlockDesigner projects (.bdproj) and Sponge schematics (.schem, v2 and v3). Litematica (.litematic) and vanilla structure (.nbt) files load too.
• Whole projects: a .bdproj loads as one schematic with its visible layers merged, each with its own offset, rotation and mirror as in BlockDesigner.
• The schematic screen (B) in four steps:
• Source: your schematic folder (or a BlockCompanion server's shared schematics), with Load, Unload and Delete.
• Placement: what is loaded, where, how far it is built, locks, show / hide, bring here, turn, mirror and Live.
• Resources: what the build still needs, and AutoBuild.
• BlockDesigner: the live link's status, Start / Stop, Get project and Send now.
• Several schematics at once, each saved per world and server with its position, turn, layer and locks.
• Locking: Position, In place (position, turning and mirroring) or Everything (the layer view too). A locked box has a blue outline.
• Save from the world: mark two corners with the stick, press O, name it, and it is saved as a Sponge v3 .schem with chest contents, signs and entities, ready to open in BlockDesigner.

A clean view

• Only what differs from the world is drawn: ghosts where a block is missing, red over a wrong block (or one facing the wrong way), orange where something is in the way. Grass, flowers, water and snow don't count as in the way.
• Ghosts use the game's own block models and your resource packs, lit by the world, slightly tinted and pulsing. Chests, signs, beds, banners, heads, shulker boxes, bells and lecterns show their real shapes; water and lava their real surface.
• The real block replaces its ghost the moment it is placed, by you or anyone else.
• Schematic boxes only show while the stick is in your hand (or always, if you prefer).
• Touching red or orange blocks share one outline and one tint, so a schematic loaded into a hillside or over an old build stays smooth.
• Built per 16x16x16 section and rebuilt only where something changed, so it stays light on the game.

Building